Test-retest reliability and time-of-day variations of perfusion imaging at rest and during a vigilance task.

Arterial spin-labeled perfusion and blood oxygenation level-dependent functional MRI are indispensable tools for noninvasive human brain imaging in clinical and cognitive neuroscience, yet concerns persist regarding the reliability and reproducibility of functional MRI findings. The circadian rhythm is known to play a significant role in physiological and psychological responses, leading to variability in brain function at different times of the day. Despite this, test-retest reliability of brain function across different times of the day remains poorly understood. This study examined the test-retest reliability of six repeated cerebral blood flow measurements using arterial spin-labeled perfusion imaging both at resting-state and during the psychomotor vigilance test, as well as task-induced cerebral blood flow changes in a cohort of 38 healthy participants over a full day. The results demonstrated excellent test-retest reliability for absolute cerebral blood flow measurements at rest and during the psychomotor vigilance test throughout the day. However, task-induced cerebral blood flow changes exhibited poor reliability across various brain regions and networks. Furthermore, reliability declined over longer time intervals within the day, particularly during nighttime scans compared to daytime scans. These findings highlight the superior reliability of absolute cerebral blood flow compared to task-induced cerebral blood flow changes and emphasize the importance of controlling time-of-day effects to enhance the reliability and reproducibility of future brain imaging studies.

Online experimental research on the psychological capital development of new venture entrepreneur under the COVID-19 pneumonia epidemic.

The global economy has been severely traumatized by the COVID-19 pandemic, and new ventures are under tremendous pressure to survive. This paper explores whether structured reading materials and mindfulness intervention can develop entrepreneurs' psychological capital and whether there are different effects on different development methods. We recruited 112 new venture entrepreneurs and carried out an online experiment using the experimental group, the control group, and the pre-test and post-test design; at last, 83 of whom participated in the process can be assessed for psychological capital development effect. The research findings indicated that structured reading materials could effectively improve the overall psychological capital of the subjects (t = -5.574，p < 0.01) and impact in every dimension, including self-efficacy (Z = -2.858, p < 0.01), hope (t = -3.560, p < 0.01), resilience (t = -4.368, p < 0.01) and optimism (Z = -3.300, p < 0.01). In comparison, mindfulness intervention can improve the subjects' overall psychological capital (Z = -3.293, p < 0.01) and improve levels of self-efficacy (Z = -2.285, p < 0.01), hope (t = -4.244, p < 0.01), resilience (t = -3.167, p < 0.01), but limited effect on the optimism (t = -1.955, p > 0.05); In addition, there is no significant difference between structured reading materials and mindfulness intervention according to the statistical analysis.